- Three main processes= erosion, transportation and deposition.
- The dominant process operating = depends on the amount of energy available.
- Governed - velocity of the flow + the amount of water flowing within the channel (discharge).
Rivers erode because they process energy.
Their total energy depends on:
- weight of the water = the greater the mass of water= more energy it will possess - the influence of gravity on its movement
- height of the river above its base level (usually sea level) = source of potential energy + the higher the source of the river =more energy
- steepness of the channel = controls the speed of the river= determines how much kinetic energy it has
Kinetic energy
Lost through :
- through friction
- internally through turbulence within the flow of the river,
- externally through contact with the bed and banks of the river channel.
Upland river channel.
Channel = rocky bed + many large boulders.
Rough shape = means that the wetted perimeter (the overall length of the bed and banks that the river is in contact with) = large.
Energy = lost through friction + the river’s velocity = energy level is reduced.
Normal conditions= unable to perform much erosion.
River contains large quantities of water following heavy rain or snowmelt= energy to perform great amounts of erosion.
